riff is a main, repeated musical phrase that often defines a song (like "Smoke on the Water"), forming its backbone, while a lick is a shorter, more decorative melodic phrase or "nugget" of notes, often improvised within solos or as fills, that can be moved between songs. Think of a riff as the essential furniture of a room, and licks as decorative pillows you can swap out; licks build solos, while riffs are the song's recognizable theme